Caracterització estructural d'una proteïna de manteniment de l'adn mitocondrial amb interès biomèdic

• Autores: Aleix Tarres Sole
• Directores de la Tesis: Maria Solà Vilarrubias (dir. tes.)
• Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2020
• Idioma: español
• ISBN: 9788449097355
• Tribunal Calificador de la Tesis: Ignacio Fita Rodríguez (presid.), David Reverter Cendrós (secret.), F Nora Vögtle (voc.)
• Programa de doctorado: Programa de Doctorado en Bioquímica, Biología Molecular y Biomedicina por la Universidad Autónoma de Barcelona
• Enlaces
  • Tesis en acceso abierto en: TDX
• Resumen

  • Abstract in English This thesis work is centred in the structural characterisation of Candida albicans (C.albicans) Gcf1p. Gcf1p is a DNA-binding protein located in C.albicans mitochondria that is essential for mitochondrial DNA (mtDNA) maintenance as well as for the viability of such organism. C.albicans is a dimorphic yeast with the capability to form invasive hyphal structures causing pathology in humans. C.albicans is a part of the mycobiota in healthy individuals. Nevertheless, it can be causing both superficial infections (candidiasis) as well as invasive infections (candidemia). Growing prevalence of candidemia, mainly caused by nosocomial transmission in hospital, together with the its high lethality (about 50% mortality rate) makes C.albicans a potential biomedical target of high interest. In addition, C.albicans and related species (Candida auris) display increasing resistance to the conventional antifungal treatments. Regarding this point, a better understanding of the fundamental mechanisms involved in mtDNA maintenance is a potential starting point for drug discovery. This thesis work provides novel information regarding how Gcf1p binds and compacts mtDNA.

    This thesis work also provides with novel information that can be of high interest in evolutionary biology. Origin and evolution of mitochondria from independent organisms to cell organelles (endosymbiotic theory) is broadly regarded by the scientific community as a key point in the apparition of eukaryotes (protists, fungi, plants and animals). The mechanisms behind mtDNA compaction and replication shows a high diversity both inter-reigns and intra-reigns. Gcf1p is also related with recombination-driven-replication mechanism present in C.albicans, which is completely different to the current model for mtDNA replication in mammals. The results provided by this thesis work in regard the union and compaction of DNA by Gcf1p suppose also a starting point for comparing the mtDNA in Candida albicans in regard of other yeast (mainly Saccharomyces cerevisiae (S.cerevisiae)) as well as in regard of distant organisms (Homo sapiens (H.sapiens)). It is also a starting point to understand evolutionary divergence amongst eukaryotes.

    This work has made use of molecular biology techniques for the cloning in plasmid vector, as well as, for the heterologous expression of yeast proteins in Escherichia coli. In addition, protein purification techniques have been applied obtaining an optimized production protocol compatible with the experimental analysis by means of structural biology methods, mainly macromolecular crystallography (MX), Small-Angle X-ray Scattering (SAXS) and Electron Microscopy (EM). Results from these three techniques provide complementary evidences about the interaction of Gcf1p with DNA.

    In summary, this tesis work provides evidences that indicate that the mtDNA recognition mechanism in C.albicans presents fundamental differences regarding those described for S.cerevisiae and H.sapiens. Our results suppose an important advance in the description of spatial organization of mitochondrial DNA, an essential process eukaryotic organism.